Reflective road markers have been employed on roads to indicate the position of the centerline and sides of a road. These markers aid drivers in distinguishing the driving surface of the road at night and in inclement weather.
There has not been any particular problems associated with the installation and use of road markers in regions that have a mild climate having normally little or no snowfall during the year. However, problems do arise in regions that have enough snowfall that require the use of snowplows to remove the snow. In removing the snow from the roads with snowplows, conventional road markers are themselves damaged or the reflective lens of the road markers are frequently broken or damaged. This creates fiscal and labor problems in replacing the reflective lens, if not the entire road marker, after every snow season.
To remedy this problem, snowplowable road markers were used in the regions having enough snow that snowplows were required for the removal of the snow. These road markers generally had a low cross-sectional profile above the road surface to allow the snowplow blade to pass up and over the road marker without damaging the reflective lens element or the road marker.
The prior art discloses reflective snowplowable road markers having various shapes and configurations. However, in almost all cases these prior art road markers are secured to the road surface by a conventional all-weather adhesive, usually having an epoxy base.
Most prior art road markers which are snowplowable have recessed reflectors to prevent their damage as the snowplow passes up and over the road marker. Prior art reflective road markers of this type that are secured directly to road surface with adhesive are disclosed in U.S. Pat. Nos. 3,938,903 and 3,499,371. These apparatus have special configurations on the bottom surface of the road marker to aid in securing the apparatus to the road surface with adhesive. Examples of other road markers which have recessed reflectors and secured directly to the surface of the roadway with adhesive which do not have special configurations on the bottom of the road markers are shown in U.S. Pat. Nos. Des. 225,087 and Des. 207,038.
The prior art also discloses reflective snowplowable road markers with recessed reflectors which have a portion of the body of marker that extends into the road material. The portions of the road markers that do extend into the road material are immersed into adhesive disposed in the opening in road to receive these portions. In U.S. Pat. No. 3,980,410, the snowplowable marker has a downwardly extending tab at each of the four corners of the snowplowable frame which are input into corresponding holes filled with adhesive. U.S. Pat. Nos. 4,195,945; 4,147,447; and 3,587,416 disclose reflective snowplowable road markers that have generally square central members which have the reflectors disposed thereon, and elongated side members attached to the central members which have portions that rise above the top of the reflectors. These elongated side members also extend below the bottom of the central member. These markers are secured to the road surface by cutting a dished-out groove with deeper elongated grooves adjacent to the edges of the dished-out groove. This area cut into the road material is then filled with adhesive and the marker is placed in it. This method is shown and described in the brochure entitled, "STIMSONITE.RTM. LIFE-LITE 96 PLOWABLE PAVEMENT MARKER."
The prior art also discloses road reflectors which have other than tabs or elongated side members that extend down into the road material. U.S. Pat. No. 4,402,628 discloses a snowplowable road marker with recessed reflectors that has a cylinder shape and secured in a core cut into the road surface by adhesive. U.S. Pat. No. 4,155,666 discloses a cylindrical shaped snowplowable road marker having recessed reflectors that is secured in either an annular recess or core cut in the road surface by adhesive. Also, at least one embodiment discloses that the marker is supported at the surface of the roadway by tabs extending from the body of the apparatus to maintain the marker in its proper position at the surface of the road while the adhesive sets up and dries. U.S. Pat. No. 3,516,337 discloses a cylindrical road marker having a tapered shaft that extend from the bottom of the marker. The shaft has projections on its outside surface. The top portion of the marker is secured to the road surface by adhesive. This shaft is secured to the road material by adhesive disposed in the hole in which the shaft is disposed. U.S. Pat. No. 2,260,498 (also U.S. Pat. No. Des. 113,298) discloses a roadway marker that has a bottom member which extends into the road material. This bottom member has a cylindrical shape with a fillet between it and the bottom surface of the top of the marker. The marker also has ribs which extend perpendicularly outward from the bottom edge of the bottom member. The marker is apparently disposed in the road material as the road is laid and not after it is laid. These markers would be extremely difficult to install.
U.S. Pat. Nos. Des. 270,143, Des. 266,554 and Des. 266,060 show other snowplowable road markers which have their downwardly extending portion secured to the road surface by adhesive.
U.S. Pat. Nos. 4,088,416 discloses a road marker that is secured to the road surface by nails or spikes.
All of the above cited prior art references have except for U.S. Pat. No. 2,260,498 (also U.S. Pat. No. Des. 113,298) and 4,088,416 have the inherent problem of requiring the use of adhesive to secure the marker to the road. These road markers cannot be installed in winter because the adhesive will not set up and dry in such cold conditions. Additionally, whenever the markers are installed, even in the correct climatic conditions, there is always a set-up and drying time for the adhesive to secure the marker in the road before normal vehicular traffic can travel over the marker.
None of the prior art markers disclosed in the prior art can be easily disposed in a core or recessed annular opening cut in the road material without the use of an adhesive to secure the marker to the road material. Further, in those apparatus that do not require the use of adhesive, as in the case of U.S. Pat. Nos. 2,260,498 (also U.S. Pat. No. Des. 113,198) and 4,088,416, the road material must either be poured around the marker or spikes driven in the road material, which is both undesirable and inefficient for installation of road markers in all seasons.
The present invention overcomes these problems and provides a snowplowable road marker which is self-securing, quick and easy to install and virtually unremovable shortly after it is installed in the road surface.